I agree about the ravens thinking dobbins can be their future, but that doesnt mean he takes over this year. or even has that huge a role
I think its honestly very smart long term planning. by long term, I dont mean for this immediate season, but rather to keep the backfield strong for the next several. there's no way to be sure Raven's extend Gus, who's a free agent after this season. Ingram is great, but it's still important to always consider the injury risk's of a 30+year old RB. It's no secret that the ravens are committed to the run. having a great RB really compliments Lamar's abilities, and its possible the Ravens want to really solidify a strength. If anything does happen to Ingram this season, after all he did suffer a late season injury last year; maybe they don't want to rely on gus and justice being their entire backfield.
But while Ingram is healthy, he can operate as the main guy, while also being a true veteran that can help dobbins with the transition. Sure, some RBs start immediately in the NFL, but its not as if that has to be the case. It's not like the ravens are in any rush to improve their offense, that was only rivaled by the chiefs for best O in the league. Rather, I think its reasonable to view dobbins as insurance for this season should anything happen to ingram / the ravens bringing in a great talent that they know theyll have for the next several years (where as gus could be gone after this year, and Ingram might only be there another year or two)

None of this should scare Ingram owners as he managed to finish as a RB1 four of the last five seasons, despite never getting more of the 55% of the backfield rushes.